it depends on how much visitors you're expecting. i'm running a site with about 2500 unique visitors a day (200000 file requests a day) and every single page is generated with 5-25 queries. we're on a virtual server with i think 50 others sites, the pages load fast and we haven't got any complaints about server load or database usage from our provider.
so i guess it won't be any problem

omen,
our provider has a dedicated mysql server, so the server load is kind of split, maybe that might be it? the last couple of days there's a noticable delay (like maybe one sec) in every page tho, but that's probably because they host almost 30000 domains in total -> they need an extra mysql server
we're thinking of getting our own dedicated server tho, since we have almost 40gig traffic/month now, and we are allowed to have 30
anyway, i think we're pushing the limit now with our site, we've been growing quite fast lately.. the site i'm talking about here is www.gizmozone.com..